1. Field of the Invention
The invention relates to an improved shock-absorbing bushing for a stirrup.
2. Description of the Prior Art
A stirrup consists of a pair of curved arms which serve as a carrier for a footrest. Each arm is joined to the other at the top end for engagement with a supporting saddle strap threaded through an eye or other connecting structure, while the bottom ends of the arms are spaced from one another and connected to a footrest to form a substantially U-shaped structure. The foot of the rider is disposed on the footrest between the spaced ends of the arms.
In a stirrup design that has been in use for several years, illustrated in FIG. 1, the arms 10 are connected at the top by means of a rigid cross member, such as a rod or bolt 12, that securely ties the arms together and provides an anchor for attachment to the saddle strap. A tubular sleeve 14, which may be made of rigid or resilient material, is used to provide a buffering structure between the rigid cross member and the strap folded around it. If resilient, the sleeve 14 also provides shock absorption. A shock-absorbing pad 16 is typically also used on top of the footrest 18.
As illustrated in the sectioned view of FIG. 2, the sleeve 14 may be assembled tightly around the rod 12, so that the forces exerted by the weight of a rider against a supporting strap 20 may be distributed over a relatively large portion of the contact area between the rod and the sleeve. In an alternative embodiment illustrated generally in FIG. 3, the sleeve 14 is provided with a larger opening than the diameter of the rod 12, thereby reducing the contact area between the two structures.
In both types of connection, the sleeve 14 surprisingly tends to wear out relatively rapidly. In the case of the tight rod/sleeve combination of FIG. 2, the compressive forces acting on the lower half of the sleeve, illustrated by arrows F in FIG. 4, cause the deterioration of the material and the subsequent loosening of the parts, which further contributes to a continuing deterioration and loss of performance. Similarly, the compressive forces acting on the embodiment of FIG. 3 produce a deformation in the sleeve 14 that soon prevents its rotation and the corresponding distribution of wear and tear around the whole body of the sleeve, as illustrated in FIG. 5, thereby also contributing to the rapid deterioration of the sleeve.
Therefore, there is a need for a better rod/sleeve type of connection for the class of stirrups illustrated in FIG. 1. This invention is directed at such an improvement.